Lecture 15 and 16 Flashcards
____________ protein catalysts that increase the overall rate of reaction without being changed in the overall process
enzymes
Enzymes convert substrates (reactants) into ______________ and channel them into useful pathways
products
*they do not invent new reactions they just increase the rate of reaction
_______ catalyze oxidation reduction reactions such as the conversion of lactate into pyruvate
oxireductase
_________ catalyze transfer of C-, N-, or P- containing groups such as serine to glycine
Transferase
_______ catalyze cleavage of bonds by addition of water
hydrolase
_________ catalyze cleavage of CC, CS and certain CN bonds such as the conversion of pyruvate to acetaldehyde
Lyases
_____________ catalyzes rearrangement of optical or geometric isomers
isomerases
______________ catalyze formation of bonds between carbon and O, S, and N coupled to hydrolysis of high energy phosphates
Ligases
Naming Enzymes
Common names: Usually have “-ase” added to the name of the substrate of the reaction and a description of the
action performed with the name of some of the substrates. Example: Lactate dehydrogenase
Systematic names: Include the names of all substrates in the reaction catalyzed and the respective class name + “ase” Example: Lactate:NAD+ oxidoreductase
Trivial namesSome retain the original trivial name, which does not give a hint as to the substrate or action.
Examples: trypsin, pepsin
Synthase vs synthetase: which one requires atp
synthase no atp
synthetase: requires atp
Oxidase vs oxygenase which one incorportes O2
‣ Oxidase – uses O2 as acceptor without incorporating it
‣ Oxygenase – one or both O2 atoms are incorporated
Phosphatase vs phosphorylase
‣ Phosphatase – uses H2O to remove phospho group
‣ Phosphorylase - add a phosphate group uses Pi to break a bond and generate phosphorylated product
_______ inorganic substances that are required for or increase the rate of catalysis
cofactors
EX: Zn2+
__________ organic molecules that are required by certain enzymes to carry out catalysis
coenzymes
Ex: vitamin derivatives: NAD+, FAD, NADP+
_____________ enzyme + non protein component (active)
Haloenzyme
____________ enzyme without non protein component (inactive)
Apoenzyme
________ the property of an enzyme to have a high turnover rate. It is the number of substrate molecules converted to product per enzyme molecule per second
Efficiency
________ only one or few substances, only one type of chemical reactions, the set of enzymes present in a cell determines which reactions will occur in the cell
Specificity
How do enzymes work
Enzymes work by lowering the free energy of activation without affecting the energies of the reactants
*they do not change the equilibrium, they accelerate equilibrium
________ a quantitative measure of the energy transfers between chemical reactions
Free Energy
______ the energy difference between that of reactants and the high energy intermediate that occurs during the formation of the product
Energy Barrier
__________ the difference in free energy between the reactant and T
Free Energy of activation Ea
_________ creates a unique microenvironment, allows for greater concentration of the intermediates that can be converted to products
stabilization of transition state
What is the difference between the lock and key model vs the induced fit model
Lock and key: enzymes active site is a rigid structure that perfectly matches the shape of specific substrate
Induced fit: proposes that the active site an enzyme can change shape slightly better to accommodate substrate upon binding making it more flexible
